Jen's In Love and Not Afraid to Show It!

Life seems like it can't get any better for Jennifer Aniston. After another spontaneous and romantic getaway--this time to Mexico--with boyfriend John Mayer, the actress returned to L.A. on Tuesday where she happily resumed what has become her daily routine these days: nesting with her much younger man!

Friends say they're blown away by this new carefree side of the actress, who uncharacteristically seems to be enjoying throwing all caution to the wind when it comes to her new relationship.

And nowhere was this more apparant than on June 12, when the cozy couple amused patrons of the trendy West Hollywood steakhouse STK with their steamy PDA!

Sitting in the most prominent booth, Jen,39, looked like she didn't have a care in the world as she giggled and nuzzled with John, nine years her junior.

"They were very cozy," an eyewitness tells OK!. "She leaned over and kissed him not just once, but twice! And it was no peck on the cheek — it was a loving, sensual kiss. They were right there, out in the open."

Say goodbye to the super-secretive Jen, who until now has led a low-key — and sometimes lonely — private life and kept her previous lovers out of the limelight.

"It's like she's a different woman," a friend of the star tells OK!. "She's more confident with herself."

Indeed, the PDA session at STK is proof positive that the 39-year-old actress has turned over a new leaf.

"Jen was the one initiating the kisses," says the eyewitness. "She hung onto John's every word and laughed at all his jokes. Jen looked like a woman in love!"

The couple's fast-moving romance definitely has Jen's pals thinking John, 30, could be "the one." As an insider tells OK!, "A lot of people who don't know John see him as aloof, but that's just the way he's always been. Even when he's dating someone seriously, he's not big on PDA. He absolutely adores Jennifer and fits right in with her friends and lifestyle."

Indeed, with a new love, and a new outlook on life, the former Mrs. Pitt seems to have finally turned a corner in 2008.

"I've never seen Jen as happy — not since the early days of her and Brad," says a friend. "If things continue down this path, I think there's a good chance she could become Mrs. Mayer."

For the entire scoop on Jen's new outlook on love, pick up the new OK!--on sale everywhere on Thursday!